Temperature-sensitive mutants of influenza A/Udorn/72 (H3N2) virus I. Isolation of temperature-sensitive mutants some of which exhibit host-dependent temperature sensitivity

Abstract

Influenza A/Udorn/72 virus was mutagenized to induce temperature-sensitive ( ts) and host range mutations. The mutagenized virus was tested on both rhesus monkey kidney (RMK) and Madin-Darby canine kidney (MDCK) tissue culture at permissive and restrictive temperatures. One hundred thirty-six ts mjtants were isolated from 6185 clones tested. Eighty-three of these were ts on RMK tissue and 133 were ts on MDCK. Each clone replicated at 34° on both RMK and MCDK tissue and thus failed to exhibit a difference in host range in these two tissues at permissive temperature. However, 32 clones were 1000-fold or more restricted in plaque formation on MDCK cultures compared to RMK culture at 38, 39, and/or 40°. Conversely, four clones were more restricted on RMK cultures. These clones represent temperature-dependent host range ( td-hr) mutants. The ts and td-hr mutants may be useful in exploring certain biological, genetic, biochemical, and pathogenic properties of influenza A virus.